Add recurring expense functionality (#263)

* code complete

* Smaller updates

* delete ambitious TODOs (add to PR)

* add transactionality to recurring expense creation

* Remove unnecessary `let`s

* Add default english labels to non-en-US translations

* Accept `es.json` translations

* add condition to ensure links are only modified when applicable

src/app/groups/[groupId]/expenses/export/json/route.ts

@@ -23,6 +23,7 @@ export async function GET(
           paidFor: { select: { participantId: true, shares: true } },
           isReimbursement: true,
           splitMode: true,
+          recurrenceRule: true,
         },
         orderBy: [{ expenseDate: 'asc' }, { createdAt: 'asc' }],
       },